Reference may be made to the following U.S. Pat. Nos. of interest: 3,214,364; 4,417,966; 3,967,131; 3,984,697; 4,504,446; 4,818,498.
Ozone has been used as a disinfectant and oxidant in industrial, commercial, municipal and recreational water use for over 80 years. One technique for producing ozone uses elongated tubular electrodes concentrically spaced from each other with an elongated tubular dielectric member concentrically spaced in between the inner and outer electrodes. In some cases, the inner electrode may consist of a surface plating on the inside surfaces of the elongated dielectric member. A feed gas, such as air or oxygen is inserted at one end of the ozone generator and in the annular gap between the outer electrode and the dielectric member. Applying a high voltage between the electrodes creates a corona discharge of the gas through the dielectric member and thereby creates ozone.
Generally, a cooling water jacket surrounds the grounded outer electrode to provide cooling for the unit. The dielectric member is typically constructed of glass or ceramic material, tubular shaped, and is supported by spring members contacting the tubular outer glass surface between the electrodes.
The corona discharge between the electrodes creates a substantial amount of heat which not only can lead to cracks in the dielectric member, but also results in inefficient ozone generation. Thus, one of the problems inherent in the typical ozone generator herein discussed is failure of the electrode assembly due to cracks in the dielectric member. Hot spots in the glass at the support spring locations and other heat induced stresses cause cracks and burn throughs leading to eventual failure of the dielectric member. This results in equipment shutdown and requires costly and time consuming repairs of the unit.
In addition, the ozone which is formed during the discharge is subject to being destroyed if maintained in the discharge zone at temperatures greater than about 130.degree. Farenheit (54.degree. Centigrade). Therefore it is desired for maximum efficiency of ozone production to maintain the gas temperatures less than 130.degree. Farenheit (54.degree. Centigrade), and preferably between about 70.degree.-90.degree. Farenheit (21.degree.-32.degree. Centigrade). Some degree of cooling is afforded by the presence of the cooling water acting on the outer electrode, but this has a minor cooling effect on the dielectric member. Secondly, while there is some cooling afforded by the feed gas which is split for simultaneously traversing in one direction the annular gaps between the outer electrode and the dielectric member, and between the dielectric member and the inner electrode, inefficient ozone production and low operating life of the dielectric member limit the usefulness of prior ozone generators.
Accordingly, it is desired to provide improved ozone generator apparatus and methods of ozone generation featuring increased reliability and high ozone generation efficiency wherein the following problems of prior units and the operation thereof are reduced or eliminated:
1. Reducing the stress and hot spots on the dielectric member due to the heat build-up during corona discharge so as to extend the life of the electrode assembly; and PA1 2. Increasing the efficiency of ozone production.